b'Figure 5. Effect of rodlet fill pressure on fission gas release.fission gas yields greater resultanthighest thermal conductivity of any fission gas concentration in theknown material, these results suggest plenum gas.These findings suggestthat doping with a good thermal that after the onset of the fission gasconductor is an effective means to release, ATF-1 test conditions arereduce fission gas release in UO 2fuels.more aggressive than typical LWR fuelBISON calculations show that ATF-1 operating conditions. experiment conditions are more Conclusions aggressive than typical LWR fuel UO 2pellets doped with 5 vol %operating conditions due to ATF-1 diamond particles were irradiatedreduced fill pressure.This finding is in the ATR at linear heat generationimportant for interpreting ATF-1 test (LHGR) of up to 310 W/cm to theresults and drawing comparisons with burnup of 7.2 GWd/tHM.Fissionthe baseline LWR fuel performance.gas release, measured during PIE, wasRecognizing that the ultimate goal of determined to be 1.08%.Fission gasATF-1 test series is screening of the release modeling performed usingearly accident tolerant fuel concepts, BISON fuel performance code showedthe more aggressive conditions of the that undoped UO 2fuel irradiatedATF-1 are fully appropriate.under the identical conditions would have had fission gas release of 9.09%.Noting that diamond has the 2019|AFC ACCOMPLISHMENTS 159'